The present invention is related to puffer-type compressed-gas circuit-interrupters of the type in which only a single gas pressure is utilized within the interrupting container structure.
As is well known by those skilled in the art, the relative motion between an operating cylinder assembly and a cooperable piston achieves a desirable compression of gas therebetween, which compressed gas is utilized during arc interruption by generally forcing the compressed high-pressure gas through a movable nozzle structure to direct the high-pressure gas flow intimately into engagement with the established arc located within the movable nozzle structure to effect the arc's extinction.
The present invention relates to puffer-type circuit interrupters of the type set forth in U.S. Pat. No. 3,551,623, issued Dec. 29, 1970, to Colcaser et al. This patent shows the relative motion of a movable piston within a relatively stationary operating cylinder, with electromagnetic field coils energizing a companion movable piston, which is electrically repelled toward the first-mentioned movable piston, the latter being attached to, and movable with, a contact-operating rod.
Other patents disclosing different piston structures, are, for example, U.S. Pat. No. 2,429,311, issued Oct. 21, 1947 to Gay; U.S. Pat. No. 3,786,215, issued Jan. 15, 1974 to Mauphe; and U.S. Pat. No. 3,987,262, issued Oct. 19, 1976, to Rostron.
U.S. Pat. No. 4,139,751, issued Feb. 13, 1979, to Rostron et al. discloses a puffer-type circuit-interrupter having a movable operating cylinder assembly movable over a relatively-fixed piston structure. A high electrical withstand capability is accomplished by using a generous radius on the lower ends of external stationary main contact fingers, and by shrouding or shielding the stationary contact probe within the surrounding shield of the stationary contact fingers. Open venting ports are provided at the upper end of the stationary contact finger cluster to prevent stagnation of the hot arc gas flowing into the stationary contact finger cluster, which thereby permits the hot arcing gases to be blown away to ensure good interrupting performance and a high breakdown value.
Another puffer-type circuit-interrupter is disclosed in U.S. Pat. No. 4,276,456, issued June 30, 1981, to Cromer et al. The Cromer patent discloses an improved circuit interrupter having an improved double-flow operation. The Cromer patent utilizes flexible movable arcing contact fingers with a surrounding cylindrical guide-valve sleeve to prevent premature leakage of compressed gas through the longitudinal finger slots provided in the movable arcing contact fingers during the opening operation.
Another puffer-type circuit-interrupter is disclosed in U.S. Pat. No. 4,219,712, issued Aug. 26, 1980, to Emmerick. The Emmerick patent discloses an interrupter including a tubular stationary contact with vent apertures in the upper portion thereof.
Although the prior art interrupters generally work well, problems have been encountered with a stagnation region forming at the stationary contact due to poor gas flow through the contact.